1. Field of the Invention
The present invention relates to a network relay apparatus.
2. Description of the Related Art
Various IP (Internet Protocol) multicast techniques have been proposed to allow a network relay apparatus to relay a multicast packet delivered from a delivery server to multiple receiving terminals. One of the proposed techniques is specifically adopted in a network configuration where multiple network relay apparatuses connect with one identical segment, in order to prevent the respective network relay apparatuses from individually relaying a multicast packet and thereby making multiple deliveries of the same multicast packet on the identical segment. One exemplified procedure of the proposed technique selects one network relay apparatus as a DR (designated router) among multiple network relay apparatuses connecting with one identical segment and specifies the selected DR network relay apparatus as a designated network relay apparatus assigned to relay a multicast packet to a receiving terminal.
With the recent spread of IPTVs (Internet Protocol Televisions) based on the IP multicast technique, remarkable increases of multicast groups and sources and a large increase of multicast packets to be transmitted are expected. This may result in increasing the processing load of the DR network relay apparatus. One known technique to overcome the load increase provides a distribution device between a receiving terminal and multiple network relay apparatuses to divide join requests for multicast groups from the receiving terminal, and thereby distributes the processing load applied by relay of multicast packets.
The above technique requires the distribution device located between the receiving terminal and the multiple network relay apparatuses on the same segment to divide the join requests for the multicast groups from the receiving terminal into the multiple network relay apparatuses. The installation of the distribution device undesirably increases the device cost and the operational cost.